PHOENIX (AP) — The owner of an Arizona shooting range says he regrets that they let a 9-year-old girl fire an Uzi submachine gun, and regrets the death of one of his instructors, who was shot and killed when the gun went out of control.

Instructor Charles Vacca was standing next to the unidentified girl Monday at the Last Stop outdoor shooting range in White Hills, Arizona, about 25 miles south of Las Vegas, when she squeezed the trigger.

Shooting range operator Sam Scarmardo said Wednesday that the girl’s parents had signed waivers saying they understood the rules of the range and were standing nearby, video-recording their daughter, when the accident happened.

Scarmardo said his policy of allowing children 8 and older to fire guns under adult supervision and the watchful eye of an instructor is standard practice in the industry.